Project Summary/Abstract Obsessional anxiety and compulsive rituals arising during pregnancy and the postpartum have a significant detrimental short-term impact on the well-being of the mother, the pregnancy, the unborn child, and the newborn infant. They also can have negative long-term effects on maternal and infant health, as well as on the mother- infant relationship and on into childhood. Although research has focused on perinatal depressive and anxious states, there is now strong evidence that obsessions and compulsions (OCS) are precipitated or exacerbated by pregnancy and childbirth and may have a deleterious impact on mother and infant. Despite an increased risk of developing OCS during pregnancy and postnatally (i.e., the perinatal period), there is almost no empirical research on its predictors and precursors, how it is related to other postpartum negative valence states such as anxiety and depression, or the specific impact of postpartum OCS on the mother. Accordingly, we will prospectively examine the predictive utility of psychological and biological phenomena (e.g., self-report, physiology) empirically linked to perinatal/postpartum OCS (pOCS), anxiety, and depression, and how these states relate with one another. We also aim to evaluate the extent to which pOCS manifest adverse effects on functionally-related outcomes of significant public health concern, such as obstetric outcomes, maternal health, maternal attitudes, and parenting behaviors during the first year of life. Consistent with the Research Domain Criteria (RDoC) framework, women will be screened antenatally for diatheses empirically demonstrated to predispose to the development or exacerbation of pOCS; and that are thus hypothesized to also put one at risk for pOCS. High- and low-risk groups will be followed during pregnancy and for 6 months postpartum, and repeatedly assessed to identify those experiencing more frequent, intense, and prolonged pOCS and the variables associated with such problems. The two recruitment sites for this study are the University of North Carolina (UNC) at Chapel Hill and Johns Hopkins University (JHU). JHU will provide data management and analytic support. Considering estimates of the high rates of pOCS, together with the limited available information on this subject, the results of this study will help clinicians and researchers 1) use psychological and biological markers elucidated in the current study to identify women at increased risk of developing OCD and its adverse consequences, and 2) reduce the risk of developing OC symptoms in pregnancy, and its adverse consequences, by modifying these psychological and biological factors prior to pregnancy, and in the early prenatal period. Moreover, the risk factors elucidated in this study may be applicable to development of non-pregnancy-related OC symptoms.